Physiological evidence supports the evidence of a wide variety of anion transporters which play essential roles in pH and ionic homeostasis in all animal cells. We have identified a family of genes related to the well characterized anion transporter of the erythrocyte, band 3. Preliminary data show that transcripts of these genes are detectable in all mammalian cells examined. The research proposed herein is concerned with the cloning of these genes and the physiological characterization of their products. We will clone cDNAs encoding these putative anion transporters from tissue-specific cell lines and determine their complete nucleotide sequences, from which the amino acid sequences will be deduced. Antibodies against defined regions of the polypeptides encoded by these genes will be raised in rabbits, and will be used to determine their tissue and cell-type specificity as well as to help define functionally important domains. Expression of the clones in Xenopus oocytes or transfected mammalian cell lines will allow us to determine their ion selectivity, pH dependence and pharmacological properties. These studies will permit, for the first time, the assignment of previously described anion transport activities to specific proteins and the elucidation of their roles in the tissues where they are normally expressed. Finally, we will continue to apply new molecular biological approaches to the identification and cloning of a broad class of genes which are likely to mediate the transport of ions across cellular membranes.